It is known for exhaust gas to be fed back to an internal combustion engine, in order to reduce emissions from the internal combustion engine. Owing to the high exhaust gas temperatures, the exhaust gas is first of all passed through a heat exchanger, which is in the form of an exhaust gas cooler, in order to cool the exhaust gas down to a temperature level which is good for combustion.
DE 197 50 588 A1 describes an apparatus for exhaust gas feedback for an internal combustion engine which has an exhaust gas cooler such as this. The exhaust gas cooler in this document has an elongated shape, and, at each of its ends, has a header plate in which the ends of a large number of tubes are inserted, which are arranged at a distance from one another. The tube bundle that is formed in this way is surrounded by a casing which is provided with connections through which the coolant is fed in and out.
The header plate at one end of the exhaust gas cooler is connected to a distribution chamber or header which tapers approximately in the form of a funnel and communicates with a large number of tubes. On the side opposite the header plate, the distribution chamber merges into a flange, which is connected to an exhaust gas pipe that further continues.
When a hot fluid is passed into the distribution chamber during operation of heat exchangers such as these, from where it flows into the tubes, the distribution chamber or a wall which surrounds the distribution chamber is heated to a greater extent than, for example, the casing which surrounds the tube bundle and through which coolant flows. The resulting thermal stresses between the distribution chamber wall and the casing in some circumstances cause leaks, in particular, at a contact point between the distribution chamber wall and the casing. Such leaks have a negative influence on the life of the heat exchanger.